Thermostatic instrument



(No Model.)

M. MARTIN. THBRMOSTATIG INSTRUMENT.

No. 497,923. Patented May 23, 1893.

UNITED STATES PATENT OFFICE.

MORRIS MARTIN, OF MALDEN, MASSACHUSETTS, ASSIGNOR TO THE UNITED STATES ELECTRIC FIRE SIGNAL COMPANY, OF PORTLAND, MAINE.

TH ERMOSTATlC INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 497,923, dated May 23, 1893.

Application filed August 9,1892. Serial No. 442,572. (No model.)

To aZZ whom it may concern:

Be it known that I, D IORRIS MARTIN, of Malden, county of Middlesex, and State of Massachusetts, have invented an Improvement in Thermostatic Instruments, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts. 1

This invention relates to thermostatic instruments, especially adapted to be employed in automatic fire alarm systems.

My present invention has for its object to provide a simple and efficient thermostatic instrument, especially adapted to be used in localities, where it is desired that the instrument should operate at a substantially low heat. In thermostatic instruments as now commonly made, a fusible solder is employed having a substantially low melting point, and it has been demonstrated by practical experience, that a solder having a melting point lower than about 150 Fahrenheit does not possess the necessary strength to enable it to be used practically.

My present invention has for its object to provide a thermostatic instrument, in which an active member, capable of being expanded or distorted by heat, is attached to a support therefor, which may be a circuit-terminal carrying body, by one or more fusible connections preferably solder, so that when the temperature has reached a predetermined point, which is lower than the melting point of the solder, the said active member will be expanded or distorted and the fusible solder ruptured, thereby operatively disconnecting the said active member from its support.

The thermostatic instrument is especially adapted to be used in an electric circuit and form an electro thermostatic instrument, which when operated, gives an alarm that the electric circuit is opened. The expanding active member referred to, is preferably made as a hermetically sealed vessel or capsule, preferably containing a volatilizable fluid, such as ether, and the said vessel is attached, as herein shown, to an electric-terminal-supporting body, it being preferably di rectly secured to the said body, by a fusible material, preferably solder, the said capsule being preferably secured directly to the circuit-terminals, and forminga part of the electric circuit. The fluid or medium contained in the vessel or capsule, is of such nature that it will volatilize at a lower heat than the melting or fusing point of the solder, and ex pand the hermetically sealed vessel and rupture the connection between the same and the circuit-terminals, and the said vessel or capsule will be forced away from the terminal supporting body, thereby opening the electric circuit at a temperature lower than the melting point of the solder.

The particular features of my invention will be pointed out in the claims at the end of this specification.

Figure l is a perspective view of a'thermostatic instrument embodying my invention,and Fig. 2, a longitudinal section of the instrument shown in Fig. 1.

A represents one form of support or circuitterminal-carrying bod y, it being herein shown as a disk of insulating or non-conducting material, provided with substantially diametrically opposite cars a, a. The body A has secured to it, as herein shown, circuit-terminals, preferably hollow tubes a a herein shown as extended into or otherwise secured to conducting tubes at a, extended down through the cars a a. The circuit-terminalcarrying body, has attached to it the active member of my improved thermostat, which active member is herein shown as a hermetically sealed vessel or capsule 17, preferably 8 containing within it a volatilizable fluid such for instance as ether, the top or upper side 1)" of the said vessel being flexible and preferably concaved, as shown in Fig. 2, to permit the said top or upper side to be bulged out, 0 when the fluid is volatilized. The vessel or capsule Z) is preferably included in the electric-circuit, and is preferably directly secured to the body A by fusible connections, such as fusible solder 12 which is herein represented 9 5 as filling the conducting tubes a a The bottom of the insulating body A is preferably made slightly convex, as shown in Fig. 2. The hollow terminals a? a are adapted to receive within them, the ends of the line wires of an electric circuit, not herein shown, and the said terminals may be electrically connected to the wires referred to, by crimp ing or bending longitudinally both the said terminals and wires, substantially as shown and described in United States Patent No. 471,130, granted to me March 22, 1892.

The fusible material or solder b as herein shown, electrically connects the hollow terminals a a with the vessel A, and when the thermostat is placed in operative position, the circuit may be supposed to pass from the terminal a through the tube a*, fusible solder b vessel 19, solder b and tube a to the terminal a In practice, the fluid b volatilizes at a lower temperature than that at which the solder or material 5 fuses or melts, so that when the fluid b is expanded bya rise in temperature, such as caused by the breaking out of a fire in a building or other structure, the cover or top 12 of the vessel will be forced against the body A by the expanding fluid, and when the said cover has obtained a solid bearing on the body A, the still expanding fluid will force the vessel 6 away from the bodyA and thereby rupture the fusible connections 22 before the latter have been melted or fused, thereby opening the electric circuit at a lower temperature, than that at which the fusible connection melts.

In practice it is desirable in many cases to have an alarm of fire at a lower temperature than 150 Fahrenheit and with the fusible thermostats as now constructed and known to me, this result cannot be obtained. In my improved thermostat the solder is weakened by even a substantially slight rise in temperature, and is therefore put into condition to be readily ruptured, when the active member is operated upon by the heat. Furthermore it will be noticed, that in case the active member should fail to operate, for any cause, the

' fusible solder would operate and open the electric circuit at the temperature at which the solder melts.

I claim 1. In a thermostatic instrument, the combination with an expansible active member, adapted to exert pressure on an increase in temperature and a support, for said active member of a fusible connection attaching said active member to the said support and normally under substantiallylittle tension by said active member but adapted to be ruptured by the increased expansive action of the active member, due to a rise in temperature, substantially as described.

2. In a thermostatic instrument, the combination with a circuit terminal-carrying body, of an expansible active member, adapted to exert pressure on an increase in temperature and one or more fusible connections attaching said active member to the said body, the said fusible connections being normally under substantially little tension by said active member but adapted to be ruptured by the increased expanding action of the active member due to a rise in temperature, substantially as described.

3. In a thermostatic instrument, the combination with a circuit terminal-carrying body, of an active member detachably attached to the said body, and consisting of a vessel containin g a volatilizable fluid, adapted to volatilize at a substantially low heat and a' fusible connection joining the said vessel to the terminal carrying body and which is ruptured by the expanding action of the vessel to open the electric circuit between the said terminals, substantially as described.

4. In a thermostatic instrument, the combination with an insulating body provided with hollow circuit-terminals a a of an expansible active member, and fusible connections joining said active member to the said body and electrically connecting the said member with the hollow terminals, substantially as described.

5. In a thermostatic instrument, the combination with the insulating body A having cars a a, of circuit terminals secured to said ears, tubes extended through the ears and to which the said circuit terminals are connected, a fluid containing vessel Z), and fusible solder securing the vessel 12 to the insulating body A and electrically connecting the said vessel with the circuit terminals, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

MORRIS MARTIN. /Vitnesses:

J As. H. CHURCHILL, A. L. ELDRIDGE. 

